This invention relates generally to star projection devices and more particularly to projectors of the type in which a light source is enclosed within an opaque enclosure having transparent regions through which light passes onto a surface to project images of the transparent regions representing stars.
Planetarium projectors of various types and configurations are well known in the art. A common projector used in public planetariums comprises a hollow opaque ball in which holes have been made to represent stars as seen from Earth. The location of the hole corresponds to the star's location, while the diameter of the hole corresponds to the star's magnitude. A light source in the ball projects the star images onto a spherical surface for viewing.
U.S. Pat. No. 3,718,992 of McGraw titled "Self-Contained Planetarium" discloses a planetarium projector in which Ptolemy's celestial sphere is projected onto an earth globe.
U.S. Pat. No. 4,178,701 of Sadler titled "Cylindrical Planetarium Projector" discloses a planetarium projector in which the light and star sheet are gimballed to change the view from Earth according to time of year.
The prior art projectors are planetariums in that they display the stars as seen from the planet Earth, i.e., their perspective is always from some point on Earth. Such projections promote a certain geocentric provincialism.